Zeolites are used in numerous industrial applications as catalysts, ion-exchangers and molecular sieves. The superior performance is often related to the presence of well-defined micropores in the zeolite structure. However, in many cases the sole presence of micropores also imposes some limitations on their applicability.
It has been shown that by introduction of a mesopore system in some or all of the zeolite crystals improved performance can be obtained in a variety of applications. Previously, this has been achieved elegantly by applying a synthesis gel with zeolite precursor composition within the pore system and on the surface of a particulate matrix having pre-determined pore structure and particle size followed by subjecting this mixture to crystallizing conditions and finally removing the matrix material.
This method has proven quite versatile, but it also has some important drawbacks. First of all, it requires that a particulate matrix with suitable pore structure is available such as expensive mesoporous carbons. Additionally, the manufacturing steps in this method are quite laborious, and finally the method is mostly applicable to the synthesis of mesoporous zeolites that are available from tetraethyl orthosilicate (TEOS) as the silicon source (U.S. Pat. No. 6,565,826).
WO-A-2004/052537 describes a method for the production of amorphous silica materials with at least about 97 vol. % mesopores, and which are prepared from a synthesis mixture containing silica source(s), heteroatom source(s) and pore-forming organic templating agent (s).